Purification of vat dyes and intermediates



Patentedreb- 6,1932 y; T i I 1,845,378

' uNITEnssrArEs HERBERT J. WEST, F GRAFTON, PENNSYLVANIA, nssIeNoE TOVITEIIZE sELDEN-coMrA Y,

F PITTSBURGH, PENNSYLVANIA, neonroEa-mronror DELAWARE I PURIFICATION or VAT EYES AN INTEEMEDIATES 1 I No Drawing. Application filed January 13, 1930.. Serial No. 420,630.

This invention relates to the purification of agentssuchas liyp'ochloritesand theprocess vat dyes of the nitrated perylene type. I is tl-lere'fore not applicable to: them. Other- The most extensively sold nitrated perylene Wisev it" is generally applicable to nitrated dye is nitrated dibenzanthrone or as its reperylenedyestuffs, for example the blue dye I duced Vat is known in the trade, indanthrene which. i s -obtainabl-e by nitrating g'isoviolan-r 83 greenB. I In the vpast the shade of this dye throne and similar nitrated perylene dyehas been considerably dulled due to the fact stuffsirrespective of- Whether the-{dye is a that the dibenzanthrone from which it is ketoni'e dye or notr i i a prepared by nitration and subsequently 're- The invention Will be described in greater, duction is made from benzanthrone by'caustic detail in connection with the following spe- ".60

fusion and only about one-half of the crude eific examples. 2 V 7 matekrial is vatable dyie, the remgining' nolrli w I Example 1 I 4 'vata le vim urities a versely a ecting t e H k. .5.

shade. It lias hitherto been-proposed to re; kllog-l ams mu fa one are thoroughly giound lnthe col 1., move these non-vatable impurities before ni- WithSOOI-t I f 1 h tmtion y a filtration ,proceissapplied-to: the 'pothiaae siiitog Ttiit 1tae i 161100 compound- Th1S.PrOceSS Products- 2 gradually until-itboils and'jit isfkept boiling purer dye but the filtration of the lmpurities for about. 10 t T1 I resents-serious difliculties so that the cost 0 mmutes' -Tw er I p mixture is filtered and the solid materlal 1 f the process. is relatively hi h although dried The yield is Over 90% of p rified MI I in the past it has been useddespitefits highj dIyeStufl I I I I I I I figsgfizialisie of the brighter shades vhlch d Cotton II on ii cellulosI'eI materialIII r yed' with the purified' dye when compare I i di i ti rgiiiil ghfhbif vit io12 55121 3; matrialldyed w h Crude ynitrrated -51 ties after nitration ofthe crude dibenzanvwlatlthrone beI-ore treafment Wlth P f throne can be so transformed by treatment ghilontle Shows? 'T R Y EW Q U t With a mild alkaline oxidizing agent suchas gf' ghz g fgg iigij l g g f gb hypochlorite as to be in part readily removd P I r b 1 I11 I able and in part transformed or destroyed m in 1s t r j ypoct so that they do not dull theshade of the dye. i? 5. order m transform m green l-dy mto At the same time colloidal material appears t t k pf Fm same (11 i pm to be destroyed so that if it is desired to fur-' i m n 9f Shade a strepgth of y ther purify the dye by filtration of the hy- 13 9 .5 2 The g'f t substantlally 25 drosulfite vat no difiiculties are encountered m t F 0 lectlonable-bmwn due to slow filterin mixture which have been" "tone 9f t e blag Whlc 1 has been so oblectlon' b able "in the past.

I so serious a drawback to the hydrosulfite fil tration of this type of dye. The process of I I I E wample 2 I the present invention uses a cheap reagent and The blue dyestufi prepared by nitrating 0 necessitates a. minimum vof manipulation. crude isoviolanthrone is treated with sodium 110 Not only is a marked increase in brightness hypochlorite or hypobromite as described in of shade obtained but the dyes appear strong- Example 1.' Theyield of purified: blue dye er and filtration troubles are practically elimstuif is likewise .90-%- or better. Cotton or inated. I regenerated cellulose material dyed with the The oxidizing treatment of the present inpurified blue dyestufi' shows a remarkable invention is generally applicable to nitrated crease inxbri'ghtnessofshade and anoticeable perylene dyestuffs With the exception of cerincrease'in strength of color whenIcompar'ed tain nitrated perylene imides and their N- withmaterialdyedw1th-the unpurifiedprodalkyl or aryl derivatives. These dyes ap- 'uct. .Aftertreatment vvithhypochlorit'e'tjopear to be attacked by alkaline oxidizing transform the blue dye nto the blaclgdye a effective, though I find that the hypohalities and particularly the hypochlorites, either preformed or in the nascent state, are the most satisfactory for practical commercial use. V v

What is claimed as new is: 1. A method of purifying a nitrated perylene dye'lorming compound which is resist-' ant to hypohalites and which contains nonvatable material, which comprises subjecting the impure nitroperylene compound tothe action vofamild alkaline oxidizer.

1 2. Amethod according to claim 1,1n which the'or-zidizing agent 1s an aqueous hypohalite solution; 1 p

r v 3. A method accordingto claim 1,1n which the oxidizing agent is an aqueous hypochlorite solution. 7

4:. A method of purifying nitrated ketonic perylene dy'etorming materials which'are attached by hypohalites which contain non} vatable'im'purities which comprises subject ing the nitrated ketonlc perylene dyeformingj material to the action of a mildalkaline 0X- idizlng agent.

5. A method according toclaim 1, in which the oxidizing agent is a hypohalite.

6. A method according to claim 4:, in which a the'orzidizin'g agent is a hypochlorite. i

7 idi'zing agent.

"Z. A method of purifying a nitrated dibenz'anthrone' compound containing non vatable impurities which comprises subjecting'it to the action of a mild alkaline ox- 8; A method according to claim 7, in which the oxidizingagent is a hypohalite.

9. A method acording to claim 7, in which the oxidizing agent is a hypochlorite.

lOQA method of purifying'nitrated Violanthrone containing non-vatable impurities whichcomprises' subjecting the nitroviolanthroneto the action of a mild alkaline oxidizing agent. v I

11. A method according'to claim 10, in which the oxidizing agent is a hypohalite,

' 12. A method according to'claim 10,7in

which the. oxidizing agent is a hypochlorite.

16. method according to claim 13, in which the oxidizing agent is a hypochlorite and the reaction takes place at about the boiling point of water.

Signed at Pittsburgh, Pennsylvania, this 11th day of January, 1930.

'- HERBERT J. WEST.

13. A method of purifyin'gnitrated violanthrone containing non-vatable impurities which comprises treating it in aqueous suspension with a hypohalite and filtering.

14. A method 'accordina to claim 13, in which the hypohalite'is a hypochlorite..

15.-A method according to claim 13, in which the reaction takes place at about the boiling point of water. 1 

